The present invention relates to a replaceable tool employed in, for example, a turret lathe or the like, and more particularly to a replaceable tool which can easily and securely attach a tool holder mounting various kinds of tools to a sleeve on a tool post.
In general, in the case of attaching a tool holder mounting various kinds of tools to a tool post and the like in various kinds of machine tools such as a turret lathe and the like, it is well-known that the simplicity of the attachment thereof and the attaching condition of the tool holder to a sleeve of the tool post seriously influence the working efficiency. By the way, as a conventional replaceable tool such as shown in Japanese Utility Model Application Kokai (=Laying-open) Publication No. 58-110303 (Applicant: Kenna Metal, Inc.) for example, proposed has been that the replaceable tool whose locking is accomplished by the method wherein a shank of the tool holder mounting various kinds of tools is inserted to a fitted hole of a sleeve attached to a machine base. An engageable ditch formed in the fitted hole of the sleeve is expanded to be engaged with a plurality of locking balls provided inside the shank and the balls are pressed in the sleeve-radial direction.
However, the above-stated conventional replaceable tool has a type of locking groove of the tool holder with the balls under the condition of pressing the balls in the sleeve-radial direction. Accordingly, it has a disadvantage that the attraction cannot be sufficiently brought about in the longitudinal direction of the sleeve, because in case the tool holder operates its attraction in the longitudinal direction of the sleeve, the force is made to be a vertical component of a force (in the radial direction of the sleeve). Further, in the case of the conventional replaceable tool, the flange portion at the rear face of the tool holder is not inevitably locked in the condition under which the balls are pressed on the fitted hole face of the sleeve. Thus, in the case of accomplishing a heavy cutting or the like, it has a disadvantage that the curving moment is operated to a tool holder so as to bring about the vibration with locking points of balls as fulcrums and thus the working efficiency is lowered.
Moreover, it has a disadvantage that, in case there exists errors in the fitted portion of the sleeve and the shank portion of the tool holder or the shank is getting smaller in a diameter on account of an abrasion or the like, it is impossible to accomplish the locking by uniformly pressing a plurality of balls on the fitted hole face of the sleeve because the rear face is made shaky by the curving moment or the like of the tool holder.